/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-  */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef _MORKCELL_
#define _MORKCELL_ 1

#ifndef _MORK_
#  include "mork.h"
#endif

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#define morkDelta_kShift 8          /* 8 bit shift */
#define morkDelta_kChangeMask 0x0FF /* low 8 bit mask */
#define morkDelta_kColumnMask (~(mork_column)morkDelta_kChangeMask)
#define morkDelta_Init(self, cl, ch) \
  ((self) = ((cl) << morkDelta_kShift) | (ch))
#define morkDelta_Change(self) ((mork_change)((self)&morkDelta_kChangeMask))
#define morkDelta_Column(self) ((self) >> morkDelta_kShift)

class morkCell {  // minimal cell format

 public:
  mork_delta mCell_Delta;  // encoding of both column and change
  morkAtom* mCell_Atom;    // content in this cell

 public:
  morkCell() : mCell_Delta(0), mCell_Atom(0) {}

  morkCell(const morkCell& c)
      : mCell_Delta(c.mCell_Delta), mCell_Atom(c.mCell_Atom) {}

  // note if ioAtom is non-nil, caller needs to call ioAtom->AddCellUse():
  morkCell(mork_column inCol, mork_change inChange, morkAtom* ioAtom) {
    morkDelta_Init(mCell_Delta, inCol, inChange);
    mCell_Atom = ioAtom;
  }

  // note if ioAtom is non-nil, caller needs to call ioAtom->AddCellUse():
  void Init(mork_column inCol, mork_change inChange, morkAtom* ioAtom) {
    morkDelta_Init(mCell_Delta, inCol, inChange);
    mCell_Atom = ioAtom;
  }

  mork_column GetColumn() const { return morkDelta_Column(mCell_Delta); }
  mork_change GetChange() const { return morkDelta_Change(mCell_Delta); }

  mork_bool IsCellClean() const { return GetChange() == morkChange_kNil; }
  mork_bool IsCellDirty() const { return GetChange() != morkChange_kNil; }

  void SetCellClean();  // set change to kNil
  void SetCellDirty();  // set change to kAdd

  void SetCellColumnDirty(mork_column inCol) {
    this->SetColumnAndChange(inCol, morkChange_kAdd);
  }

  void SetCellColumnClean(mork_column inCol) {
    this->SetColumnAndChange(inCol, morkChange_kNil);
  }

  void SetColumnAndChange(mork_column inCol, mork_change inChange) {
    morkDelta_Init(mCell_Delta, inCol, inChange);
  }

  morkAtom* GetAtom() { return mCell_Atom; }

  void SetAtom(morkEnv* ev, morkAtom* ioAtom, morkPool* ioPool);
  // SetAtom() "acquires" the new ioAtom if non-nil, by calling AddCellUse()
  // to increase the refcount, and puts ioAtom into mCell_Atom.  If the old
  // atom in mCell_Atom is non-nil, then it is "released" first by a call to
  // CutCellUse(), and if the use count then becomes zero, then the old atom
  // is deallocated by returning it to the pool ioPool.  (And this is
  // why ioPool is a parameter to this method.)  Note that ioAtom can be nil
  // to cause the cell to refer to nothing, and the old atom in mCell_Atom
  // can also be nil, and all the atom refcounting is handled correctly.
  //
  // Note that if ioAtom was just created, it typically has a zero use count
  // before calling SetAtom().  But use count is one higher after SetAtom().

  void SetYarn(morkEnv* ev, const mdbYarn* inYarn, morkStore* ioStore);

  void AliasYarn(morkEnv* ev, mdbYarn* outYarn) const;
  void GetYarn(morkEnv* ev, mdbYarn* outYarn) const;
};

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#endif /* _MORKCELL_ */